testsuite: Fix up pr121987.c testcase for ilp32 [PR121206]

testsuite: Fix up pr121987.c testcase for ilp32 [PR121206]

The test FAILs on ilp32 targets with
pr121987.c:5:21: warning: unsigned conversion from 'long long int' to 'long unsigned int' changes value from '10000000000' to '1410065408' [-Woverflow]
excess error.  Fixed by using unsigned long long instead of unsigned and
using a suffix on the constant.
Tested on x86_64-linux with -m32/-m64, additionally tested with older cc1
where it ICEd in both cases in upper_bound.

2025-10-08  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/121206
	* gcc.dg/pr121987.c (main): Use unsigned long long type for e instead
	of unsigned long and use ULL suffix on the initializer.